Photo-curing refers to a process in which a matrix of a monomer, an oligomer, or a polymer is cured under the light induction, and this technology has a wide use in modern micro-electronic technologies, for example, photo-cured inks, packaging of liquid crystal panels, photosensitive printing plates, color filters, photoresists, and the like. The key point of photo-curing technology lies in photo-curable polymerizable monomers and suitable photoinitiators. Under the irradiation of a light source having a certain wavelength, a photoinitiator generates an active group, which excites an unsaturated group in a polymerizable monomer so that a polymerization reaction occurs, and thereby leads to the curing of the material.
The photoinitiator is a paramount factor which affects the photosensitive property of a photo-curable composition (i.e., a photosensitive composition). At present, there have been a number of studies and reports concerning the photoinitiators. However, these photoinitiators generally have a low photosensing activity, and has serious limit in terms of the type of the applicable light sources. Most of them are only suitable for ultraviolet excitation. For example, there exists oxime ester type photoinitiators, such as a carbazolyl oxime ester type photoinitiator disclosed in CN101508744A, a commercially available oxime ester type photoinitiator OXE-02, a ketoxime ester type photoinitiator disclosed in CN101565472A, a commercially available ketoxime ester type photoinitiator OXE-01, etc., all of which only meet the requirement for applications using a mercury lamp (including high-pressure, middle-pressure, and low-pressure mercury lamps) as the exposure source.
Along with the increase of awareness and requirement for environment and safety, as well as the development of the photopolymerization technology, exposure lamp sources being low-energy, high-safety, energy-saving, and environmentally friendly such as LED, LDI, etc., have become a trend in the application and the development of technologies in this field. Under this situation, it has important practical and economic meanings to research and develop a photoinitiator capable of matching low-energy and long-wavelength-output exposure sources such as LED, LDI, etc. At present, none of the current photoinitiators may well match the exposure sources such as LED, LDI, etc., and a low photosensitivity (i.e., photosensing activity) is exhibited.
In view of this, this invention discloses a carbazolyl ketoxime ester type photoinitiator, this type of photoinitiator may not only match the light sources of mercury lamps, but also may well match low-energy and long-wavelength-output exposure sources such as LED, LDI, etc., and has a very high photosensitivity.